Integrated Roles of MoS2 Nanosheets for Water Treatment and Polymer Flame Retardant

Abstract

Layered MoS2 nanosheets have been widely investigated for wastewater treatment or polymer flame retardant alone, while few reports concern about their integrated utilization within the two fields. Herein, the authors creatively explored the multiple roles of MoS2 nanosheets for simultaneous water treatment and polymers flame retardant. MoS2 nanosheets were firstly employed as adsorbents for heavy metals removal and organics elimination in wastewater. The adsorption capacities of MoS2 for methylene blue (MB) and methyl orange (MO), Co2+, Ni2+, were found 181.8, 102.1, 61.7 and 51.8 mg/g, separately, due to the chemical and electrostatic interactions. Then the MoS2 nanosheets after water treatment (MoS2−x) were blended into polystyrene (PS) to study their flame-retardant properties and integrated utilization explorations. Results based on thermal stability, smoke suppression and heat resistance revealed that MoS2−x/PS composites displayed slower heat release rate (HRR), smaller smoke production rate (SPR) and lower CO production rate (COP) but higher T−10% than that of pristine PS, demonstrating the excellent flame-retardant efficiency of MoS2−x. Mechanisms for the great promotion in flame-retardant properties were found mainly resulted from nano-barrier and block wall effect of MoS2−x. Meanwhile, the rapid formation of char residue during the combustion also contributed to the improvement. Investigations in the present work implied the MoS2 nanosheets could not only remove heavy metals and organics, but also can simultaneously delay the polymer combustion, demonstrating the excellent integrated and multiple roles of MoS2 nanosheets in water remediation and polymer flame retardant.